$1.$ What is an alpha particle? $(1)$

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$2.$ For the Rutherford Atom Simulation, how are the atomic and nuclear simulations different? $(1)$

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$3.$ Why does the simulation start with $79$ protons? $(1)$

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$4.$ Use the Rutherford simulation $($nuclear scale$)$ to change the following variables and record your observations. $(3)$